An overdensity of Lyman break galaxies around the hot dust-obscured galaxy WISE J224607.56−052634.9

Abstract

We report the identification of Lyman Break Galaxy (LBG) candidates around the most luminous Hot Dust-Obscured Galaxy (Hot DOG) known, WISE J224607.56−052634.9 (W2246−0526) at z = 4.601, using deep r-, i-, and z-band imaging from the Gemini Multi-Object Spectrograph South (GMOS-S). We use the surface density of LBGs to probe the Mpc-scale environment of W2246−0526 to characterize its richness and evolutionary state. We identify LBG candidates in the vicinity of W2246−0526 using the selection criteria developed by Ouchi et al. (2004) and Yoshida et al. (2006) in the Subaru Deep Field and in the Subaru XMM-Newton Deep Field, slightly modified to account for the difference between the filters used, and we find 37 and 55 LBG candidates, respectively. Matching to the z-band depths of those studies, this corresponds to δ = 5.8 +2.4 −1.9 times the surface density of LBGs expected in the field. Interestingly, the Hot DOG itself, as well as a confirmed neighbor, do not satisfy either LBG selection criteria, suggesting we may be missing a large number of companion galaxies. Our analysis shows that we are most likely only finding those with higher-than-average IGM optical depth or moderately high dust obscuration. The number density of LBG candidates is not concentrated around W2246−0526, suggesting either an early evolutionary stage for the proto-cluster or that the Hot DOG may not be the most massive galaxy, or that the Hot DOG may be affecting the IGM transparency in its vicinity. The overdensity around W2246−0526 is comparable to overdensities found around other Hot DOGs and is somewhat higher than typically found for radio galaxies and luminous quasars at a similar redshift.

Physical Properties of Hyperluminous, Dust-obscured Quasars at z ∼ 3: Multiwavelength Spectral Energy Distribution Analysis and Cold Gas Content Revealed by ALMA

“…The X-ray observations of Hot DOGs consistently find high column densities that are close to Compton thick (Stern et al 2014;Piconcelli et al 2015;Assef et al 2016;Ricci et al 2017;Vito et al 2018;Zappacosta et al 2018;Assef et al 2020). The environments where Hot DOGs reside were found to be significantly overdense (Jones et al 2015;Silva et al 2015;Jones et al 2017;Penney et al 2019;Ginolfi et al 2022;Luo et al 2022;Zewdie et al 2023). All results are generally consistent with the merger-driven coevolution scenario.…”

Black Hole Mass and Eddington Ratio Distribution of Hot Dust-obscured Galaxies

“…Studies have increasingly shown that Hot DOGs reside in overdense environments, characterized by a high frequency of galactic mergers (Jones et al 2014;Jones 2017;Assef et al 2015;Díaz-Santos et al 2018;Penney et al 2019;Luo et al 2022;Ginolfi et al 2022;Zewdie et al 2023). Despite hosting powerful AGNs, the host galaxies of high-z Hot DOGs are gasrich (Penney et al 2020;Díaz-Santos et al 2021;L.…”

“…By imaging the [C II] emission in extremely luminous DOGs (L bol > 10 14 e ) ALMA, however, Díaz-Santos et al (2021) proposed instead that this short-lived phase may be triggered by a minor merger and might occur recurrently throughout the history of the galaxy. This is particularly plausible if Hot DOGs become the brightest galaxies in clusters once the overdensities they live in (Jones et al 2014;Jones 2017;Assef et al 2015;Luo et al 2022;Ginolfi et al 2022;Zewdie et al 2023) become virialized.…”